The invention relates to catalytic converters for treating exhaust gases, and especially to converters capable of handling large gas volume applications such as large stationary engines. It is economically desirable, due to the relatively small numbers of large engines made, to utilize ceramic monolithic catalyst elements of the type developed and extensively tested for automotive use. However, a 2000 HP engine may require 100 or more of such automotive type elements. Since the single element mounting structures used for automotive applications would be extremely expensive, there would appear to be a need for a good economical mounting system for mounting a plurality of ceramic elements in a large converter housing. Such a mounting system should be light and inexpensive to fabricate, able to prevent bypass leakage designed for easy field change of the catalyst elements, and durable through many temperature cycles even though the ceramic and metal parts have widely different coefficients of thermal expansion. One system which eliminates the converter housing and the metal mesh blanket which typically surrounds the ceramic element is disclosed in my U.S. Pat. No. 4,250,146 which is assigned to a common assignee. However, the patented system is most useful for mounting a single element in that it utilizes at least three springs and at least three fasteners to bias a pair of end support elements towards the ceramic catalyst support element and towards each other. It would be quite cumbersome to adapt such a system to a large converter installation although far less costly than the use of a plurality of housed elements.